Randall J Erickson

US Patent:

40553779, Oct 25, 1977

Filed:

Aug 3, 1976

Appl. No.:

5/711140

Inventors:

Randall L. Erickson - North Oaks MN
Terry R. Bailey - Cottage Grove MN

Assignee:

Minnesota Mining and Manufacturing Company - St.Paul MN

International Classification:

G02B 5128

US Classification:

350105

Abstract:

Novel magnetically orientable retroreflectorization particles permit application of highly oriented retroreflective coatings. The retroreflectorization particles individually comprise at least one transparent microsphere, specular reflective means in optical connection with a first portion of said microsphere so as to provide retroreflection of light incident on the opposed portion of the microsphere, and a magnetic layer underlying said specular reflective means and having a magnetic axis parallel to the optical axis on which said first and opposed portions of the microsphere are aligned. When the particles are applied to a substrate in the presence of a magnetic field having flux lines of appropriate polarity perpendicular to the substrate, the particles tend to become aligned in a common direction that retroreflects light incident on the coating.